Fred W. Lindemans

Adverse Events With Transvenous Implantable Cardioverter-Defibrillators A Prospective Multicenter Study

BACKGROUND A newly developed classification system relates adverse events to the surgical procedure or the function of the implantable defibrillator. METHODS AND RESULTS Adverse events were monitored during prospective clinical evaluation of the Medtronic model 7219 Jewel ICD and were classified according to the definitions of the ISO 14155 standard for device clinical trials into 3 groups: severe and mild device-related and severe non-device-related adverse events. In addition, events were related to the surgical procedure, treatment with the device, or cardiac function. Seven hundred seventy-eight patients were followed up for an average of 4.0 months after ICD implantation. In total, 356 adverse events were observed in 259 patients. At 1, 3, and 12 months after ICD implantation, 99%, 98%, and 97% of the patients, respectively, survived; 95%, 93%, and 92%, respectively, were free of surgical reintervention; and 79%, 68%, and 51%, respectively, were free of any adverse event. Twenty patients died: 6 deaths were related to the surgical procedure, 12 deaths were considered unrelated to ICD treatment, and 2 patients died of an unknown cause. Of 111 nonlethal severe adverse device effects, 47 required surgical intervention, 19 times for correction of a dislodged lead. Inappropriate delivery of therapy was observed 128 times in 111 patients, and the events were typically resolved by reprogramming or drug adjustment. Nine of these required rehospitalization. CONCLUSIONS Approximately 50% of patients experience an adverse event within the first year after ICD implantation. The observed adverse event rate depends on the definitions and the prospective monitoring. The incidence of inappropriate therapy emphasizes the need for improved detection algorithms and for quality-of-life evaluations, especially when considering ICD treatment in high-risk but arrhythmia-free patients.

Risk stratification for sudden cardiac death: current status and challenges for the future

Sudden cardiac death (SCD) remains a daunting problem. It is a major public health issue for several reasons: from its prevalence (20% of total mortality in the industrialized world) to the devastating psycho-social impact on society and on the families of victims often still in their prime, and it represents a challenge for medicine, and especially for cardiology. This text summarizes the discussions and opinions of a group of investigators with a long-standing interest in this field. We addressed the occurrence of SCD in individuals apparently healthy, in patients with heart disease and mild or severe cardiac dysfunction, and in those with genetically based arrhythmic diseases. Recognizing the need for more accurate registries of the global and regional distribution of SCD in these different categories, we focused on the assessment of risk for SCD in these four groups, looking at the significance of alterations in cardiac function, of signs of electrical instability identified by ECG abnormalities or by autonomic tests, and of the progressive impact of genetic screening. Special attention was given to the identification of areas of research more or less likely to provide useful information, and thereby more or less suitable for the investment of time and of research funds.

Pacemaker Related Tachycardias

Three cases of pacemaker interactive tachycardia are presented. The first two are (artificial) circus movement tachycardias. In the first one the retrograde arm of the tachycardia circuit was provided by the A‐V node and the antegrade arm by an atrial synchronous pulse generator. In the second case, the A‐V node and, coincidentally, an A‐V sequential pulse generator alternately provided the antegrade arm while the retrograde arm was by way of an accessory pathway. In the third case ventricular inhibition during A‐V sequential pacing gave the paced atrial events the chance to be conducted to the ventricles with a long A‐V interval. This resulted in a tachycardia with a rate of 150 bpm, instead of the programmed rate of 110 bpm. (PACE, Vol. 5, July‐August, 1982)

Holter Documented Sudden Death in a Patient with an Implanted Defibrillator

A 68‐year‐old man with recurrent attacks of monomorphic ventricular tachycardia (VT) received a pacer cardioverter defifarillalor featuring antitachycardia pacing and cardioversion/defibrillation. Over 300 episodes of VT were successfully terminated by antitachycardia pacing. During Holter monitoring the patient experienced supra ventricular tachycardia with delivery of multiple antitachycardia pacing, cardioversion, and defibrillation therapies ending with the death of the patient. The following factors played a role in the unfortunate outcome of this patient: 1. triggering of VT therapy by an unexpected high sinus rate; 2. atrial fibrillation induced by cardioversion therapy; 3, a gradual and continuous increase in rate during atrial fibrillation possibly caused by repeated VT and ventricular fibrillation therapies and/or by a thrombus, found at autopsy, in a bypass graft; and 4. the limited ability of presently available defibrillators to distinguish between ventricular and supraventricular arrhythmias.

Pacemaker Syndrome with AAI Rate Variable Pacing: Importance of Atrioventricular Conduction Properties, Medication, and Pacemaker Programmability

A patient who received an AAI Activitrax rate variable pacemaker for treatment of symptomatic sinus bradycardia is described, disopyramide prolonged the anterograde effective refractory period of the fast conducting atrioventricular (AV) nodal pathway to such an extent, that conduction switched to the slow AV nodal pathway at low atrial pacing rates. This gave rise to symptoms of the pacemaker syndrome during moderate exercise because the paced atrial event was conducted with a long, spike to Q interval with occurrence of the paced atrial event just after the preceding QRS complex. A change of medication solved this problem. Programming a bipolar electrode configuration avoided sensing of far‐field QRS signals with the associated problems of resetting the basic pacing interval as well as the upper rate interval. AAI rate variable pacing requires careful evaluation of AV conduction properties, AV conduction intervals as well as the influence of medication to be given. The use of multiprogrammable pacemakers with marker channel capability will significantly facilitate the understanding and resolution of anomalous behavior.

Clinical Experience with an Activity Sensing Pacemaker

During clinical evaluation of the Medtronic * Activitrax pacemaker in a worldwide multicenter study, implant and follow‐up data were provided by 61 investigators on 222 patients. Pacing indications included two‐ and three‐degree AV block in 149 and atrial arrhythmias in 174 patients; 16 patients received atrial pacing. Average and longest documented follow‐up periods were 7.5 and 16 months respectively. Paired treadmill tests, one in Activity mode and one in VVI/AAI mode, were performed by 120 patients. At peak exercise, average heart rate was 95 bpm in VVI/AAI mode and 118 bpm in Activity mode (p < 0.0001). Average exercise time was 9.4 minutes in VVI/AAI mode and 10.8 minutes in Activity mode (p < 0.0001). In 54 patients who exclusively had paced rhythm during both treadmill tests, average heart rates and exercise times were 70 ppm and 8.1 minutes in VVI/AAI mode and 111 ppm and 10.3 minutes in Activity mode respectively (p < 0.0001). 24‐hour Holter recordings typically demonstrated pacing at or near basic rate during periods of rest and appropriate increase in pacing rate during daily activities. Patients had significantly fewer problems with physical effort in daily life during a week of Activity mode pacing than during a week of VVI/AAI mode pacing (p < 0.05) as assessed from the symptom scores recorded by 62 patients in special diaries.

Clinical Experience with Implantable Devices for Control of Tachyarrhythmias

Pacing is becoming an accepted form of treatment for reentry tachycardias. The different pacing modalities available and experience with a patient‐activated antitachycardia pacemaker are presented in this paper. This system has bidirectional communication between pacemaker and pacemaker‐activator and between pacemaker and prescription formulator (which is a sophisticated portable stimulator used for non‐invasive electrophysiological evaluation of the system). This pacemaker was implanted in 18 patients with drug‐resistant tachycardias. Six patients had ventricular tachycardia, 3 had A‐V nodal reentrant tachycardia, 4 had the concealed accessory pathway, and 5 had the WPW syndrome. In the 3 months before implantation the mean number of admissions for termination of tachycardia was 2.1 per patient‐month. During a follow‐up period of 3–26 months only 6 patients were admitted once for termination of tachycardia (0.02 admissions per patient‐month). The reasons for admission of these 6 patients were: defective pacemaker activator in 2 patients, inadequate control of tachycardia in 2 patients, inappropriate use of the device in 1, and inadequate intake of medication in 1. All these problems were solved easily. Eight pacemaker activators required reprogramming, which was done in 5 patients on an out‐patient basis. The interval scanning mode was used in 9 patients. Nine patients required more than 2 stimuli for reproducible termination. A step‐wise increase in number of stimuli was used in 5 patients.

A versatile pacemaker system for termination of tachycardia

Abstract Externally activated pacemaker systems were implanted in 13 patients to control their drug-resistant tachycardias. Four patients had ventricular tachycardia, 2 had atrioventricular nodal reentrant tachycardia, 3 had tachycardias due to a left-sided concealed accessory pathway and 4 had Wolff-Parkinson-White syndrome. Nine patients were paced from the right ventricle, 2 from the right atrium and 2 from the coronary sinus. The pacing system consisted of an implantable pacemaker, an external pacemaker activator and a prescription formulator. The pacemaker can signal sensing by way of radiofrequency signals to the pacemaker activator or prescription formulator. Either 1 of the latter 2 devices then determines whether the sensed rhythm fulfills the tachycardia detection criteria and, if so, controls the delivery of the selected stimulation treatment by the pacemaker. With this bidirectional radiofrequency coupling, tachycardias were noninvasively initiated by the prescription formulator after implantation and at follow-up visits to test and eventually reprogram the pacemaker activator. During a follow-up of 116 patient-months, 624 episodes of tachycardia were effectively terminated by the patients. Incidental failure to terminate occurred in 3 patients because of a defective activator, changes in the electrophysiologic substrate and inappropriate use of the device. These problems were solved by reprogramming, replacement of the activator and education of the patient. Hospital admissions for termination of tachycardia decreased from an average of 2.6 per patient-month (in the 3 months before implantation) to 0.03 per patient-month after implantation (follow-up 4 to 16 months). It is concluded that (1) this programmable externally activated pacemaker system effectively manages drug-resistant tachycardia; (2) this system has the advantage of easy testing, multiple pacing modes and ready reprogrammability; and (3) the marked reduction in hospital admissions makes the system cost-effective.

Management of Pacemaker Circus Movement Tachycardias

DDD pacemakers were implanted in 11 patients of whom 5 had the capacity to conduct retrogradely to the atrium. Methods to prevent or terminate pacemaker circus movement tachycardia (PCMT) were evaluated in these patients. V‐A conduction was assessed before implantation by incremental right ventricular pacing while recording right atrial electrograms. Following implantation and at quarterly outpatient clinic visits, V‐A conduction and ability to initiate and sustain PCMT were systematically assessed by non‐invasive techniques. PCMT could be induced non‐invasively in all 5 patients. The methods used to reduce and terminate the incidence of PCMT were: 1) decreasing the atrial sensitivity; 2) stressing the V‐A conduction system by programming a high upper rate with an appropriately short A‐V interval; 3) programming a low lower rate; 4) avoiding the Wenckebacb response (by programming a high upper rate); 5) medication; and 6) occasionally by using a magnet. PCMT was controlled in all patients, in 2 patients by programming measures only and in 2 with the addition of medication. One patient who refused medication had to be programmed into another pacing mode. We conclude that : 1) the presence of V‐A conduction is not an absolute contraindication to the use of a DDD pacing system; 2) pacing the ventricle early enough to cause V‐A block was the most useful method to terminate PCMT; 3) future generation DDD pacemakers should prevent initiation of PCMTs while maintaining the possibility to synchronize to exercise‐induced high atrial rates.

The activitrax rate responsive pacemaker system

Bipolar Medtronic Activitrax rate responsive pacemakers were implanted in 31 patients for ventricular (28) or atrial (3) pacing. Mean follow-up was 16 months (range 10 to 26). Twenty pacemakers were implanted after catheter ablation of the His bundle, 7 for sick sinus syndrome. 1 for atrioventricular block and 3 for sick sinus syndrome with atrioventricular block. A rate response value was selected that gave a pacing rate of about 100 pulses/min during walking. Of the 31 patients, all had 24-hour ambulatory electrocardiographic monitoring with diary, 11 walked a 20-minute circuit, including a flight of stairs, and 20 had a treadmill exercise test. In 9 patients the pacing rate could be compared with the underlying sinus rate during exercise and was seen to match it very closely. In 12 patients the pacing rate during car driving was found to be similar to the sinus rate of 5 volunteers under similar conditions (mean minimum and maximum rate was 80 and 99 pulses/min, respectively). No pacing-induced arrhythmias were seen during ambulatory electrocardiographic monitoring. At high pacing rates slightly irregular pacing intervals were sometimes observed, which was due to polarization sensing. Sporadically, 1 pacing interval shortened to the upper rate value, because of a known and now resolved timing anomaly. Neither anomaly was of clinical consequence and the first could be resolved by reprogramming.(ABSTRACT TRUNCATED AT 250 WORDS)